ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

Co-developed-by: Qi Xi <xiqi2@huawei.com>

Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/input/Makefile b/drivers/input/Makefile
new file mode 100644
index 000000000..2cd6e1c9a
--- /dev/null
+++ b/drivers/input/Makefile
@@ -0,0 +1,32 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the input core drivers.
+#
+
+# Each configuration option enables a list of files.
+
+obj-$(CONFIG_INPUT)		+= input-core.o
+input-core-y := input.o input-compat.o input-mt.o input-poller.o ff-core.o
+input-core-y += touchscreen.o touch-overlay.o
+
+obj-$(CONFIG_INPUT_FF_MEMLESS)	+= ff-memless.o
+obj-$(CONFIG_INPUT_SPARSEKMAP)	+= sparse-keymap.o
+obj-$(CONFIG_INPUT_MATRIXKMAP)	+= matrix-keymap.o
+obj-$(CONFIG_INPUT_VIVALDIFMAP)	+= vivaldi-fmap.o
+
+obj-$(CONFIG_INPUT_LEDS)	+= input-leds.o
+obj-$(CONFIG_INPUT_MOUSEDEV)	+= mousedev.o
+obj-$(CONFIG_INPUT_JOYDEV)	+= joydev.o
+obj-$(CONFIG_INPUT_EVDEV)	+= evdev.o
+
+obj-$(CONFIG_INPUT_KEYBOARD)	+= keyboard/
+obj-$(CONFIG_INPUT_MOUSE)	+= mouse/
+obj-$(CONFIG_INPUT_JOYSTICK)	+= joystick/
+obj-$(CONFIG_INPUT_TABLET)	+= tablet/
+obj-$(CONFIG_INPUT_TOUCHSCREEN)	+= touchscreen/
+obj-$(CONFIG_INPUT_MISC)	+= misc/
+obj-$(CONFIG_INPUT_KUNIT_TEST)	+= tests/
+
+obj-$(CONFIG_INPUT_APMPOWER)	+= apm-power.o
+
+obj-$(CONFIG_RMI4_CORE)		+= rmi4/